Fixtures of the type used, for example, in the fields of painting and electroplating represent a major investment for businesses that engage in the painting or electroplating of objects. It has heretofor been necessary to fabricate the fixtures or racks, as they are called in the art, to meet the precise physical support requirements of the objects or parts to be processed. This "specialization" of rack design is especially cumbersome to the custom paint or electroplating shop of the type which accepts job contracts. Such a shop or business must of necessity not only maintain an extensive inventory of special and general purpose racks, but still must maintain the means, either by in-house fabrication facilities or by purchase, to obtain additional specialty racks or fixtures.
Fixtures heretofore used in electroplating and painting have also had the problem of being inefficiently constructed. The inefficiencies lie in two distinct areas. First there is the inefficiency of welded, brazed or mechanically fastened means for holding the part supporting members to a main conducting bar which is usually made from copper. In a typical construction found in the prior art, copper bars of approximately one-half inch square cross-section (12.5 mm by 12.5 mm) are joined at right angles in a cross shape by drilling and tapping the bars and through bolting at the intersection. The process of drilling and tapping removes a portion of the electrical conduction path of the copper bars causing inefficiencies and non-uniform electrical current distribution in the bars. This also results in less current being transmitted to the parts held in the fixture. Object/part holders, or tips as they are called in the art, are attached to the conducting bars in a similar fashion.
Second is the inefficiency of construction. The labor intensive steps of drilling, tapping or even of brazing the bar intersection joints and tips into the fabricated rack or fixture considerably add to the cost of the final fixture and to the costs which must be charged by the business. Even minor modification of the rack to suit new purposes can be an involved and labor intensive process. Additionally, inventoried racks represent a large amount of copper which is not being efficiently utilized, but which has heretofor been stored with the inventoried racks.
An additional problem encountered on fixtures or racks which are used to position, support or retain objects to be electroplated or especially painted, is that materials of the process (i.e., paint or coating materials) build-up on the fixture and can drip, under the action of gravity, on the objects being processed.
Therefore, there is a need for a method of constructing fixtures or racks in which the bars and tips from which the racks are constructed may be easily connected and disconnected from one another. There is also a need for an apparatus for attaching bars and tips to one another such that both the bars and the tips can be reused. There is also a need for a method and apparatus for constructing electroplating racks in which the conducting bars and tips may be joined together without the removal of, interference with or reduction of the electrical path, while maintaining good electrical contact between the respective bars and tips.
There is also a need for a utility type of bar from which objects to be painted or electroplated may be suspended which protects the objects from dripping paint or materials which build-up on the fixture or rack.
There is additionally, a need for easily constructed, easily stored and reusable painting racks and fixtures for reasons similar to those stated above, since the problems of the electroplating industry are shared by the painting industry, whether electrostatically charged painting systems are utilized or not.
Further, there is a need for painting and/or electroplating racks and fixtures which are easily assembled yet can be broken down into unit construction pieces for easy, low volume, shipping from fabricator to user.
Electroplating racks additionally are subject to being themselves plated. This problem has been solved in the prior art by covering the completely fabricated rack with a plastic or similar coating which is impervious to the electroplating bath and is electrically non-conductive, Unfortunately, the solution of the electroplating bath is often partially lost by being siphoned between the rack and its protective coating by a strong capillary action. This also leads to destruction of the rack as the solution is passed directly over the metal surfaces.
Therefore, there is a need for an apparatus and method for, preventing the initiation of such siphoning by capillary action.